Balloon dissecting instruments

ABSTRACT

Balloon loaded dissection devices with elongate balloons and a pushing member are disclosed for creating a tunnel alongside an elongate vessel in the body. The devices may utilize an elongate balloon of any suitable length which may be formed of an elastic or non-elastic material. The balloon may be of double walled construction and may be provided with a central lumen which may receive a guide rod, scope or other surgical instrument. The device may have a support tube secured to the inner wall of the balloon to provide columnar support for the apparatus. The support tube receives the guide rod, scope or other surgical instrument and may have a stop member to translate pushing force applied to the guide rod or scope to pushing force on the apparatus. By using the guide rod or scope as a pushing member the apparatus may be advanced alongside the vessel it is desired to dissect free from attached tissue. A balloon cover which may be elastic or resilient is provided to surround the balloon and facilitate compression of the balloon after it is deflated. In an additional feature, the guide rod and/or tubular member are plastically bendable into a curved shape such that the balloon dissector may be adjusted into a curved shape.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of copending U.S. application Ser. No.08/688,044, filed on Jul. 29, 1996 now abandoned, which is acontinuation-in-part of U.S. application Ser. No. 08/447,124, filed onMay 22, 1995 now U.S. Pat. No. 5,702,417. The priority of these priorapplication is expressly claimed and their disclosure are herebyincorporated by reference in their entirely.

FIELD OF THE INVENTION

This invention relates to methods and devices for endoscopic vascularsurgery, in particular to methods and devices for dissecting tissue tocreate a working space adjacent a blood vessel.

BACKGROUND OF THE INVENTION

Numerous surgical procedures have been developed to replace arteriesthat have become blocked by disease. The aortocoronary bypass surgery isperhaps the most important of these bypass operations. The coronaryarteries supply blood to the heart. As a result of aging and disease,coronary arteries may become blocked by plaque deposits, stenosis, orcholesterol. In some instances, these blockages can be treated withatherectomy, angioplasty or stent placement, and coronary bypass surgeryis not required. Coronary bypass surgery is required when these othermethods of treatment cannot be used or have failed to clear the blockedartery. In coronary bypass surgery, a vein is harvested from elsewherein the body and grafted into place between the aorta and the coronaryartery below the point of blockage. An illustration of this surgery isshown in FIG. 1, which shows the heart 1 and the right anterior coronaryartery 2 and the left anterior coronary artery 3 which supply blood tothe heart. The right anterior coronary artery 2 is blocked in itsproximal segment at 2a, as shown. This blockage has been bypassed bygrafting a segment of vein 4 between the aorta 5 and the distal segment2b of the right anterior coronary artery 2. Similarly, the left anteriorcoronary artery 3 may be blocked, and may require bypass with a lengthof vein 4a between the aorta and the distal segment 3b of the leftanterior artery. The operation requires access to the heart, which meansthat the chest cavity must be opened completely.

The coronary bypass surgery requires a length of vein or artery for thegraft. It is preferred to use a vein taken from the patient undergoingthe bypass surgery. The patient is a ready source of suitable veins thatwill not be rejected by the body after transplantation and grafting ontothe aorta and coronary artery. The saphenous vein in the leg is the bestsubstitute for small arteries such as the coronary arteries, and it isthe preferred vein for use in coronary bypass surgery. This is becausethe saphenous vein is typically 3 to 5 mm in diameter, about the samesize as the coronary arteries. Also, the venous system of the legs issufficiently redundant so that after removal of the saphenous vein,other veins that remain in the leg are adequate to provide return bloodflow. The cephalic vein in the arm is an alternative that is sometimesused.

A typical operation previously required to harvest the saphenous vein isillustrated in FIG. 2. The surgeon cuts into the leg to allow access tothe saphenous vein and cuts the vein from the leg. To expose thesaphenous vein 6, the surgeon makes a series of incisions from the groin7 to the knee 8 or the ankle 9, leaving a one or more skin bridges 10along the line of the incisions. Some surgeons make one continuousincision from the groin to the knee or ankle. Handling of the vein mustbe kept to a minimum, but the vein must be dissected free fromconnective tissue. After exposing the vein, the surgeon grasps it withhis fingers while stripping off the surrounding tissues with dissectingscissors or other scraping instruments. The surgeon uses his fingers andblunt dissection tools to pull and lift (or mobilize) the vein from thesurrounding tissue. The vein is mobilized or pulled as far as possiblethrough each incision. To reach under the skin bridges, the surgeonlifts the skin with retractors and digs the vein free. While strippingthe vein, the surgeon will encounter the various tributary veins thatfeed into the saphenous vein. These tributaries must be ligated anddivided. To divide and ligate tributaries that lie under the skinbridges, the surgeon may need to cut one end of the saphenous vein andpull it under the skin bridge to gently pull the vein out from under theskin bridge until the tributary is sufficiently exposed so that it maybe ligated and divided. When the vein has been completely mobilized, thesurgeon cuts the proximal and distal ends of the vein and removes thevein from the leg. After removal, the vein is prepared for implantationinto the graft site, and the long incisions made in the leg are stitchedclosed.

The procedure described above can be used to harvest veins for a femoralpopliteal bypass, in which an occluded femoral artery is bypassed fromabove the occlusion to the popliteal artery near the level of the knee.The procedure can also be used to harvest veins for therevascularization of the superior mesenteric artery which supplies bloodto the abdominal cavity and intestines. In this case, the harvested veinis inserted between the aorta to the distal and patent (unblocked)section of the mesenteric artery. For bypass grafts of the lowerpopliteal branches in the calf, the procedure can be used to harvest theumbilical vein. The harvested vein can also be used for a vein loop inthe arm (for dialysis) between the cephalic vein and brachial artery.

As can be seen from the description above, the vein harvesting operationis very traumatic in its own right. In the case of coronary arterybypass, this operation is carried out immediately before the open chestoperation required to graft the harvested vein into the coronaryarteries. The vein harvesting operation is often the most troublesomepart of the operation. The long incisions created in the leg can be slowto heal and very painful. Complications resulting from the veinharvesting operation can also hinder the patient's recovery from theentire operation.

The method of vein harvesting presented herein is accomplished withlaparoscopic procedures. This allows the veins to be harvested in anoperation that requires only a few small incisions. Endoscopic surgicaltechniques for operations such as gall bladder removal and hernia repairare now common. The surgeon performing the operation makes a few smallincisions and inserts long tools, including forceps, scissors, andstaplers, into the incision and deep into the body. Viewing the toolsthrough a laparoscope or a video display from the laparoscope, thesurgeon can perform a wide variety or maneuvers, including cutting andsuturing operations, necessary for a wide variety of surgical proceduresand operations.

Minimally invasive procedures for vein removal have been proposed. U.S.Pat. No. 5,373,840 to Knighton, entitled, "Endoscope and Method for VeinRemoval," shows a method of cutting the saphenous vein at one end, andgrasping the vein with graspers or forceps, then sliding a ring over thevein while holding it. Knighton uses a dissecting tool with an annularcutting ring, and requires that the saphenous vein be overrun orprogressively surrounded with the dissecting tool and the endoscope, sothat after the endoscope has been inserted as far as it will go, theentire dissected portion of the vein has been pulled into the lumen ofthe endoscope. As shown in FIGS. 1 and 10 of Knighton, the methodrequires deployment of forceps inside the annular dissection loop, andit requires deployment of the loop and graspers inside the endoscopelumen. The blood vessel must be cut and grasped by the forceps before itcan be dissected by the dissecting ring.

SUMMARY OF THE INVENTION

The methods and devices disclosed herein allow surgeons to harvestveins, or dissect along other elongate structures without making longincisions through the skin to access the structure as previouslyrequired. The present devices permit minimally invasive procedureswhich, in the case of a saphenous vein harvest, require just two smallincisions, one at either end of the saphenous vein, to be performed. Theprocedure is accomplished with laparoscopic instruments under theguidance of a laparoscope.

In a first preferred embodiment, a blunt loaded balloon dissector has anelongate balloon of any suitable length which may be formed of anelastic or non-elastic material. The balloon may be of double walledconstruction and may be provided with a central lumen which may receivea guide rod, scope or other surgical instrument. The device may have asupport tube secured to the inner wall of the balloon to providecolumnar support for the apparatus.

The guide rod and/or support tube are normally straight and must be asufficient rigidity to bluntly dissect while tunneling between connectedtissue layers. In a further aspect of the present invention, the guiderod and/or support tube, while being rigid enough to bluntly dissect,are also plasticly bendable into curved shapes when subjected to bendingmoments substantially greater than the bending moments encountered whendissecting between tissue layers. The guide rod and/or support tubepermanently retain the curved shape under the forces and conditions ofblunt dissection. The support tube receives the guide rod, scope orother surgical instrument and may have a stop member to translatepushing force applied to the guide rod or scope to pushing force on theapparatus. By using the guide rod or scope as a pushing member theapparatus may be advanced alongside the vessel it is desired to dissectfree from attached tissue. A balloon cover which may be elastic orresilient is provided to surround the balloon and facilitate compressionof the balloon after it is deflated.

In another embodiment of the invention, another pushable balloondissection device is provided which also may utilize an elongateballoon. The balloon in this embodiment may have a central lumen toreceive a scope or other laparoscopic instrument. The apparatus has aguide tube which receives a guide rod with a slender metal rod andenlarged tip. The guide rod is utilized as a pushing member. A resilientballoon cover may also be provided in this embodiment to compress theballoon upon deflation.

In yet another preferred embodiment of the invention, a pushable balloondissection apparatus may have an elongate balloon disposed over anelongate shaft or tubular member such that the shaft or tubular memberresides within the interior space of the balloon. The balloon dissectormay be advanced between the tissue planes it is desired to dissect andthen inflated to create a tunnel alongside a vessel or other elongatestructure. The balloon may then be serially deflated, further advancedand reinflated to enlarge the tunnel. When the apparatus is providedwith a tubular member, a laparoscope may be inserted into the bore ofthe tubular member and utilized as a pushing member to advance theapparatus and to provide observation of the procedure. A resilientballoon cover may also be utilized in this embodiment to assist indeflating and compressing the balloon to facilitate redeployment of theapparatus.

The method of vein harvesting disclosed herein utilizes an elongatetubular balloon to dissect a tunnel alongside the vein to be harvested.The elongate balloon may be wrapped around a guide rod or endoscope andinserted through a small incision in the leg and pushed along the veinto create a small tunnel over the vein. The elongate balloon may beprovided with a balloon cover which may be a separate removable cover orattached to the balloon. When the balloon is in place adjacent the veinto be dissected, the removable balloon cover (if provided) may beremoved and the balloon inflated to enlarge the tunnel and create aworking space for insertion of endoscopic instruments. The guide rod orendoscope may be removed to allow other endoscopic instruments to bepassed into the tunnel through the balloon.

In a preferred method of harvesting the saphenous vein, the surgeonmakes one small incision at each end of the saphenous vein. After makingthe incisions, the surgeon inserts a tunneling instrument or bluntdissector which carries a long balloon into one incision and advances orpushes the dissector along the saphenous vein to make a small tunnelalong the saphenous vein. The surgeon then inflates the long balloon toenlarge the tunnel. When the tunnel is enlarged to an appropriate size,the surgeon removes the balloon and seals the tunnel at both ends. Thesurgeon may then injects carbon dioxide into the tunnel at sufficientpressure (typically 5-15 mm Hg) to inflate the tunnel and create roomfor laparoscopic instruments. The surgeon then inserts a laparoscopethrough the seal to provide a view of the procedure, and inserts alaparoscopic vein harvesting device, such as one of the hooked veinharvesting devices disclosed in copending U.S. application Ser. No.08/444,424 entitled, "Methods and Devices for Blood Vessel Harvesting,"into the leg to dissect the connective tissue from the vein, identifyside branches, and remove the vein from the leg. The disclosure of theaforementioned application Ser. No. 08/444,424 is hereby incorporated byreference in its entirety. After the vein is loosened or dissected freefrom its channel in the leg, the surgeon can cut the proximal and distalends of the vein and easily pull the vein from the leg. The small skinincisions are then stitched so that they may heal. The small incisionsheal much more readily, with fewer complications and far less pain, thanthe open procedures now in use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of the heart showing a vein grafted from theaorta to the right anterior coronary artery, bypassing the proximalsegment of the right anterior coronary artery.

FIG. 2 is a view of the leg showing the incisions necessary forharvesting the saphenous vein using a traditional open procedure.

FIGS. 3, 3a and 3b are views of the leg showing the incisions necessaryfor harvesting the saphenous vein according to the methods presentedherein.

FIG. 4 shows a balloon dissector according to the invention uninflatedand ready for insertion.

FIG. 5 shows a balloon dissector according to the invention in itsinflated state.

FIG. 6 is a cross-section of an alternate embodiment of a balloondissector according to the invention in its uninflated state.

FIG. 7 is an isometric view of a balloon dissector according to theinvention, illustrating the balloon dissector in its expanded state.

FIG. 8 is a view of the balloon dissector illustrated in FIG. 7 with aresilient balloon cover surrounding the elongate balloon.

FIG. 9 is an isometric view of another embodiment of a balloon dissectoraccording to the invention with visualization capability illustrated inits expanded state.

FIG. 10 is a view of the balloon dissector illustrated in FIG. 9 with aresilient balloon cover surrounding the elongate balloon.

FIG. 11 is a perspective view of a balloon dissector having a bendableguide rod and support tube according to the invention.

FIG. 12 is a perspective view of a balloon dissector having a bendableguide rod according to the present invention.

FIG. 13 is a perspective view of a balloon dissector having a bendabletubular member according to the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 4 shows an embodiment of a balloon loaded blunt dissector 15 in itsuninflated state, with a balloon 16 packed inside the device. Theballoon 16 is a nonelastic balloon or bladder and is cylindrical ortubular with a central lumen 17. The balloon 16 has two walls 18 and 19and may be described as a double walled balloon tube. The balloon 16 maybe made of polyethylene, polyurethane, polyamide and other nonelasticmaterials as well as latex and other elastic materials. The balloon 16may be any suitable length, for example 12 to 24 inches long, to provideof a tunnel of convenient length when harvesting the saphenous vein. Theballoon 16 may be any convenient diameter or width, for example 2 to 3inches, to allow laparoscopic instruments to fit and operateconveniently within the tunnel created by the balloon 16. The balloontube 16 may have any suitable cross-sectional shape.

A guide rod 20 with a blunt or rounded tip 21 is disposed in the centrallumen 17 of the double walled balloon tube 16. The guide rod 20 is usedas a pushing member to push the balloon 16 through body tissue. Asupport tube 22 may be provided to give some columnar support to thedevice and provide a stop member or coupling member to translate pushingforce applied to the guide rod 20 to pushing action on the balloon tube16. The support tube 22 may be secured to the inner wall of the balloontube 16 in any suitable fashion. The support tube 22 may have anoverhanging lip 23 which obstructs passage of the guide rod 20 orendoscope 29 (if provided). Alternatively, the guide rod 20 or endoscope29 can be fitted with a stop collar 30 to engage the support tube 22 (asshown in FIG. 5). The support tube 22 may have a square tip 25 as inFIG. 4 or a rounded tip 26 as shown in FIG. 5. The guide rod 20 andsupport tube 22 are used to push the balloon 16 along the saphenous veinor other desired pathway between tissue layers.

The guide rod 20 and support tube 22 are normally straight (as shown inFIG. 4) and are of sufficient rigidity to bluntly dissect between tissuelayers. In addition, the guide rod 20 and support tube 22 may beconfigured such that they are plastically bendable into curved shapeswhen subjected to bending moments substantially greater than the bendingmoments encountered when used to dissect between tissue layers (see FIG.11). The bendable guide rod 20 and/or support tube 22 are made ofmaterials and are proportioned such that they permanently retain thecurved shape and have sufficient rigidity in the curved shape to bluntlydissect between tissue layers. In this way, the dissector 15 can be bentinto a desired segment of dissection alongside a curved elongatestructure or to maneuver the dissector 15 around an obstruction blockingthe path to the area to be dissected. Use of the support tube 22 permitsthe guide rod 20 or endoscope 29, if utilized as the pushing member, tobe removably received by the apparatus 15. This allows the apparatus 15to use fairly expensive and nondisposable devices such as the endoscopeas the pushing member. If visualization is not needed or desired, theballoon 16 may be sealed to a disposable pushing member and may becoupled to the pushing member with adhesives, heat sealing or integralconstruction or any other coupling means. A balloon cover 27 surroundsthe balloon tube 16 and provides a protective sheath during placement ofthe balloon loaded dissector 15. The balloon cover 27 may be a thinsheath of polyethylene or other plastic film, or it may be a more rigidtube of PVC, PTFE, PETG, polyethylene or other plastic.

The balloon cover 27 may be elastic or resilient so that it serves tocompress the balloon 16, so that the balloon 16 quickly andautomatically collapses upon deflation. The balloon cover 16 may be maderesilient by choosing a resilient material such as a thin sheet ofpolyethylene which is sufficiently resilient and elastic under thepressure used to inflate the balloon 16. The balloon 16 itself may alsobe made of polyethylene, and may be a thick polyethylene which isnonelastomeric under range of pressure used to inflate the balloon 16.When the balloon 16 and balloon cover 27 are made of the same materialor a miscible material, the balloon 16 may be heat sealed to the ballooncover 27 at various points to prevent the balloon cover 27 frominadvertently slipping off the balloon 16. When the balloon 16 andballoon cover 27 are made of different or immiscible materials, they maybe attached with adhesive or through the use of other suitablefasteners.

In the preferred embodiment of a method of using the devices disclosedherein, the surgeon uses a balloon loaded dissector to create a workingspace under the skin and over the saphenous vein suitable forlaparoscopic techniques. The surgeon makes one or more incisions asshown in FIG. 3, to expose the saphenous vein. These incisions arereferred to as cut-downs. An incision at the knee 12, an incision at thegroin 13, or an incision close to the ankle 14 can be used. In FIG. 3,the saphenous vein 6 can be seen through the cut-downs 12, 13 and 14. Itwill be apparent from the description that the use of three or fourincisions to harvest the entire saphenous vein is merely a matter ofconvenience, and those particularly skilled in laparoscopic proceduresmay require fewer incisions, and smaller incisions than illustrated maybe required.

If the dissector 15 is configured with a bendable guide rod 20 andsupport tube 22, the surgeon first bends the guide rod 20 and supporttube 22 into the desired shape.

After insertion, the balloon loaded blunt dissector 15 is pushed alongthe blood vessel until the balloon tube 16 is located over the desiredlength of the saphenous vein. When the balloon 16 is properly in placeit occupies a narrow tunnel over the saphenous vein. When in place, theballoon 16 is inflated through inflation tube 28. As shown in FIG. 5,the outer walls expand under inflation and the balloon cover 27stretches as the balloon 16 is inflated. The expansion of the balloon 16enlarges the tunnel. The outer diameter of the balloon tube 16 definesthe size of the tunnel that is created, and the outer diameter may becontrolled during manufacture and during inflation. Also as shown inFIG. 5, the guide rod 20 may be conveniently replaced with an endoscope29 which can also serve as the pushing member. The endoscope 29 can bechosen to have an outer diameter matching the support tube, or it can beprovided with a stop collar 30, both constructions serving to couple theendoscope 29 to the balloon tube 16 so that pushing on the endoscope 29serves to push the balloon 16 into the body.

When the balloon 16 is deflated through the inflation tube 28, theballoon cover 27 serves to compress and collapse the balloon 16 andsqueeze the inflation fluid out of the balloon 16, thus returning theballoon 16 to the collapsed state shown in FIG. 4. After the balloon 16has been collapsed by the elastic force of the balloon cover 27, thedevice 15 may be further advanced or pulled-back from its position inthe body, and repositioned at another area of interest. When the balloon16 is repositioned, it may be reinflated to enlarge the tunnel. Theballoon 16 may be repeatedly inflated and deflated in this manner.Alternatively, the balloon cover 27 may be removed by pulling itproximally out of the incision to allow the balloon 16 to expand.

FIG. 6 shows an alternate embodiment of a balloon loaded bluntdissector. The guide rod 31 is provided with a slender metal rod 32fitted with an enlarged tip or olive tip 33. The guide rod 31 may bereplaced by a scope if visualization is desired. The balloon 34 is along slender cylindrical balloon, with or without a central lumen. Aguide tube 35 is attached to the outside of the balloon 34 and the guiderod 31 fits through the guide tube 35. The balloon 34 is uninflated inFIG. 6, and the balloon 34 and guide tube 35 are shown inside theballoon cover 27. The balloon 34 of FIG. 6 is used in the same way asthe balloon 16 of FIGS. 4 and 5.

In operation, the apparatus is slipped over an endoscope (if utilized)or guide rod 31 and the balloon cover 27 is slipped over the apparatus.It is expected that use of an endoscope will be preferred, because itallows for visualization of the anatomy at its distal tip as theapparatus pushes through the fat layer overlying the saphenous vein. Theapparatus is inserted either directly into the incision or is introducedthrough a cannula. After the guide rod 31 and balloon 34 are in placeover the blood vessel, the balloon cover 27 can be pulled out of theincision, and may be provided with a weakened section to facilitateremoval. The balloon cover 27 may be pulled back gradually as theballoon 34 is inserted to uncover that portion of the balloon 34 whichis inside the body, and the balloon 34 can be inflated to dissect alarger tunnel in the early stages of insertion. The balloon cover 27 mayalso be left in place and, if made of a resilient material, can be usedto compress the balloon 34 after deflation to facilitate repositioningof the assembly.

After full insertion, in a preferred method of use, the balloon 34 maybe left in place in the tunnel while the endoscope is utilized to viewthe interior surfaces of the body at the tip of the apparatus, as shownin FIG. 3a. If the balloon 34 is provided with a central lumen,endoscopic instruments may be passed through said central lumen toperform surgical procedures on body parts such as the saphenous vein andcommunicating veins of the leg. In situations where it is desirable toinsufflate the tunnel created by the balloon 34, the balloon 34 may bedeflated and pulled out of the tunnel through cut-down 13, and a cannulaport 36 with insufflation tube 37 may be inserted into the same cut-downas shown in FIG. 3b. A secondary endoscopic access port 38 may beinserted into the knee incision 12 to pass a variety of instruments intothe work space.

The step of removing the balloon cover 27 may be avoided if the ballooncover 27 is perforated along a number of longitudinal lines and sealedto the balloon 34 along longitudinal lines, so that expansion of theballoon 34 tears the balloon cover 27 to allow expansion, but the piecesstay fixed to the balloon 34 so that they may be removed easily.

Another embodiment of a balloon dissection apparatus 50 is illustratedin FIG. 7. In this embodiment, the balloon dissector 50 includes ahandle 52, a tunneling rod 54 which may be provided with a blunt tip 56,and an elongate balloon 58 having an inflation harness 60 extending fromthe balloon 58. The tunneling shaft 54 is normally straight and isformed of a suitable material such as surgical stainless steel toprovide adequate rigidity for the shaft 54 to serve as a blunt obturatorfor tunneling between tissue layers.

In a further of the present invention, the tunneling shaft 54 may beplastically bendable into curved shapes (see FIG. 12). The bendabletunneling shaft 54 is constructed so that it permanently retains thecurved shape and has sufficient rigidity in the curved shape to bluntlydissect between tissue layers. Then, similar to the dissector 15described above, the dissector 50 can be bent into a curved shape tofacilitate the dissection procedure (see FIG. 12). For example, thedissector 50 may be curved to approximate the shape of an elongatestructure it is desired to dissect free of connective tissue, or tofacilitate the maneuvering of the dissector around an obstruction.

When the balloon dissector 50 is configured as an extraluminal balloondissector to harvest the saphenous vein in the leg, for example, thetunneling shaft 54 may have a length of about 12 inches, and a diameterof approximately 1/8 inch. Alternatively, the tunneling shaft 54 may beformed from a semi-flexible material, such as plastic, for example, toaccommodate situations where it is desirable to provide a tunnelingshaft with the capability to navigate somewhat torturous passages withinthe body. The tunneling shaft 54 may be mounted in the handle 52 usingany suitable fastening system, e.g., gluing or a compression fit. Theblunt tip 56, which may be integrally formed with the tunneling shaft 54or a separate member, provides a blunt distal end on the tunneling shaft54. Although an olive-shaped tip 56 is illustrated, other shapesproviding a blunt surface are possible. The blunt tip 56 may also beomitted.

The elongate balloon 58 has distal and proximal ends 59 and 53 and aneck portion 57 extending from the proximal end 53 of the balloon 58.For the purposes of this application, an elongate balloon is defined asa balloon having an axial length substantially greater than itstransverse diameter when the balloon is inflated. As illustrated in FIG.7, the elongate balloon 58 is mounted over the tunneling shaft 54 suchthat the tunneling shaft 54 lies within the interior space 63 of theballoon 58. The distal end 59 of the balloon 58 is preferably providedwith a nipple or pocket 61 that may mate against the distal tip 56 ofthe tunneling shaft 54 to help protect against stretching or tearing ofthe distal tip of the balloon during tunneling. As will be describedbelow, this construction permits the tunneling shaft 54 to be used as apushing member to advance the deflated balloon 58 alongside a bloodvessel or other elongate structure it is desired to dissect free ofconnected tissues.

The neck portion 57 of the balloon 58 may be secured inside the handle52 in a fluid-tight fashion. Alternatively, the neck portion 57 may besecured to the tunneling shaft 54 by any suitable bonding system such asgluing or clamping. When the neck portion 57 is mounted in the handle 52as illustrated in FIG. 7, the balloon inflation harness 60 may extendfrom the neck portion of the elongate balloon 57 to provide a fluidpassageway into the interior space 63 of the balloon 58.

One example of a suitable balloon inflation assembly is illustrated inFIG. 7 in the form of balloon inflation harness 60. Balloon inflationharness 60 includes a tube 68 which extends from the balloon 58 and isconnected to a wye fitting 70. A luer-type fitting with check valve 67,is connected to one port of the wye fitting 70 and an evacuation fitting69 is connected to the other port of the wye fitting 70. A pinch clamp66 is provided to close off the fluid passageway from the wye fitting 70to the evacuation fitting 69. The balloon inflation harness 60illustrated is of the same type as described in copending applicationSer. No. 08/570,766, filed on Dec. 12, 1995, the disclosure of which ishereby incorporated by reference in its entirety. Of course, numerousother suitable balloon inflation assemblies are possible.

In the FIG. 7 example, the elongate balloon 58 is inflated by closingthe pinch clamp 66 and injecting a suitable inflation fluid, preferablysaline solution, although other fluids such as air may be utilizedinstead, through the fitting 67 into the balloon inflation lumen 68,which is in communication with the interior space 63 of the balloon 58.

As one alternative to the balloon inflation harness 60, the handle 52may be provided with an inflation port which is in communication withthe proximal end of the neck portion 57 of the elongate balloon 58. Inthis alternative embodiment, inflation fluid is injected through theinflation port in the handle 52 directly into the neck portion 57 of theballoon 58.

The balloon 58 is preferably constructed of a medical gradenonelastomeric material of suitable type such as a polyurethaneaccording to known fabrication techniques so as to have a predeterminedelongate shape. Although all nonelastomeric materials exhibit somedegree of elasticity, for the purposes of this application, anonelastomeric material is one which remains substantially inelasticover the desired inflation pressure ranges utilized for the particularprocedure. Although an elastomeric balloon may be utilized with theballoon dissector 50, it is preferable to use an inelastic balloon sothat the expansion envelope of the balloon can be more preciselypredicted. In contrast, an elastomeric balloon tends to inflatefollowing the path of least tissue resistance and localized differencesin tissue resistance may cause an undesirable aneurysm in the balloonleading to nonuniform dissection.

In a preferred method of use, an incision is made in the body proximatethe elongate structure within the body it is desired to dissect free ofconnective tissue. The surgeon identifies the appropriate tissue planesdissection is desired to occur along and the balloon dissector 50 isinserted, either directly or with the aid of a cannula, through theincision into the body and advanced following the identified tissueplanes. If the balloon dissector 50 is configured with a bendable guiderod 54, then prior to insertion into the body, the surgeon bends theguide rod 54 into the desired shape. The surgeon uses the handle 52 andpushes the balloon dissector 50 as a blunt obturator following thetissue planes adjacent the elongate structure until a desired locationfor deployment of the dissector 50 is reached. As the dissector 50 isadvanced within the body, its progress may be monitored through the skinby direct observation and/or manual palpation. Depending on theprocedure, varying amounts of the overall length of the elongate balloon58 may be disposed within the incision.

Once the desired location for dissection has been reached through blunttunneling, the elongate balloon 58 may be inflated by closing the pinchclamp 66 and communicating an inflation fluid through the ballooninflation harness 60 into the interior space 63 of the balloon 58. As itinflates, the balloon 58 expands into the predetermined elongate shapeand dissects tissue away from the elongate structure to create a tunnelalongside the elongate structure. After the tunnel has been created, thedissector 50 may be deflated by releasing the pinch clamp 66 andapplying vacuum to the male evacuation fitting 69. After deflation, thedissector 50 may be removed from the body through the incision, orfurther advanced alongside the elongate structure and reinflated toenlarge the tunnel.

After the dissector has been removed from the body, a cannula and skinseal assembly of the type disclosed in application Ser. No. 08/570,766,for example, may be inserted into the incision and the skin sealadvanced into the incision to create a substantially gas-tight seal withthe incision. The space created by the balloon dissector 50 may then beinsufflated by injecting an appropriate insufflation gas through a portprovided on the cannula should an insufflated operating space bedesired.

Use of the dissector 50 specifically contemplates multiple serialballoon dissections. The dissector 50 may be advanced into the body instages along the identified natural tissue planes by repeatedlyadvancing and deploying the dissector 50 to dissect a tunnel of thedesired length alongside the elongate structure. The process ofadvancing the dissector 50, inflating the balloon 58, and deflating theballoon 58 may be repeated in serial fashion until the desired tunnelhas been created. In the embodiment of the balloon dissector 50illustrated in FIG. 7, a vacuum may be drawn on the balloon 58 todeflate and contract the balloon 58 so that the dissector 50 can berepositioned and redeployed as needed.

The balloon dissector 50 is illustrated in FIG. 8 with an elastomericballoon cover 72 that surrounds the elongate balloon 58. The dissector50 is in all other respects identical to the FIG. 7 embodiment. Thecover 72 preferably has a diameter such that when the balloon 58 is in adeflated condition, the cover 72 compresses the balloon 58 around theshaft 54. The use of the cover 72 thus aids in the serial redeploymentof the balloon 58 by automatically causing the balloon to return to acompressed state upon deflation. The elastomeric cover 72 may be formedfrom a resilient material such as a thin sheet of polyurethane which issufficiently resilient and elastic under the pressure used to inflatethe balloon 58, or it may formed from an elastomer such as silicon orlatex rubber.

The cover 72 may be bonded to the balloon 58 at various points usingknown bonding techniques to prevent the cover 72 from inadvertentlyslipping off the balloon 58. Alternatively, the cover 72 may have adiameter closely matching the diameter of the shaft 54 so that the cover72 is retained in position by its elastic compression on the shaft 54,or by friction. The cover 72 may also completely cover the elongateballoon 58 and be secured in the handle 52. In this case, the cover 72may be inflated independently of the elongate balloon 58 to provide aballoon with elastomeric characteristics, i.e., localized tissueexpansion following the path of least tissue resistance.

As an alternative embodiment, the elongate balloon 58 may be elastic andthe cover 72 may be inelastic such that the inelastic cover 72 acts tolimit expansion of the elongate balloon 58.

It is also possible to utilize a separate removable cover of the typedisclosed in co-pending application Ser. No. 08/570,766, for example, oran integral balloon cover which separates upon expansion of the balloonas described with reference to previous embodiments.

Another embodiment of a balloon dissector 80 is illustrated in FIG. 9.The balloon dissector 80 differs from the balloon dissector 50 only inthat the tubular member 82 replaces the tunneling shaft 54 and anopening in communication with the bore in the tubular member 82 isprovided in the handle 52. As shown in FIG. 13, the tubular member 82may be bendable and have similar characteristics, as described for thebendable tunneling shaft 54, described above. In this embodiment, thetubular member 82 serves as a scope cover to provide the dissector 80with visualization capability when used in conjunction with alaparoscope. The tubular member 82 has an internal diameter, such as 10mm for example, sized to receive a conventional laparoscope. The tubularmember 80 may be formed of any suitable material, such as plastic forexample.

The tubular member 82 may have an open distal end 84 as illustrated inFIG. 9 to permit observation with the laparoscope through the opendistal end 84. As shown in FIG. 9, the open distal end 84 of the tubularmember 82 may be cut away at a 45 degree angle, for example, andprovided with a lip 86 which serves to capture the distal end of thelaparoscope when inserted to prevent the laparoscope from extendingbeyond the open distal end 84. Alternatively, the open distal end 84 ofthe tubular member 82 may be squared off and the lip 86 provided byrolling the open distal end inward. The distal end of the tubular member82 may also be closed and rounded if visualization through an opendistal end is not desired.

An instrument seal, which may comprise an area of reduced internaldiameter in the tubular member 82, may be provided to prevent theballoon inflation fluid from leaking out of the handle 52 during ballooninflation. Alternatively, or in combination with the area of reduceddiameter in the tubular member 82, an instrument seal of the typeillustrated in application Ser. No. 08/570,766 may be provided in thehandle 52.

In addition to the balloon inflation options described with regard tothe FIGS. 7 and 8 embodiments, the elongate balloon 58 of the dissector80 may be inflated by injecting the inflation fluid through an inflationport in the handle 52 directly into a lumen in the tubular member 82. Ifthe tubular member 82 has the presently preferred open distal endconstruction, the inflation fluid may be communicated through the borein the tubular member 82 and out the open distal end 84 into theinterior space 63 of the balloon 58. If a closed-ended tubular member 82is utilized, inflation may be through a separate lumen formed in thewall of the tubular member 82 which opens into the interior space 63 ofthe balloon 58.

To prepare for tunneling dissection, a laparoscope, which may be aconventional 10 mm laparoscope, for example, is inserted through thehandle 52 and advanced into the bore of the tubular member 82 until thedistal extremity of the laparoscope is captured by the lip 86 in theopen distal end 84 of the tubular member 82. The lip 86 in the opendistal end 84 thus prevents the laparoscope from being advanced beyondthe open distal end of the tubular member 82. Although an angled scopewill provide the best visualization through the open distal end 84 ofthe tubular member 82, a straight scope may also be utilized.

The balloon dissector 80 is then inserted through the incision andtunneled bluntly following the desired tissue planes using thelaparoscope and tubular member 82 as a blunt obturator. The procedure tobe followed is the same as previously described with regard to the FIGS.7 and 8 embodiments with the exception that the progress of theoperation may be observed through the laparoscope during tunnelingdissection. During the tunneling stage, the distal end of thelaparoscope looks out through the open distal end 84 of the tubularmember 82 obstructed by only a single and preferably transparent layerof the elongate balloon 58. Moreover, when the balloon 58 is inflated tocreate a tunnel alongside the desired elongate structure, thelaparoscope may be utilized to observe the progress of the dissection.

FIG. 10 illustrates the addition of a resilient cover 72 to the balloondissector 80 having visualization capabilities. The cover 72 may be ofthe same construction as previously described and may function in anequivalent manner to automatically compress the elongate balloon 58about the tubular member 82 upon deflation.

The balloon loaded devices disclosed herein can be used in otherprocedures besides dissection for vein harvesting. The description ofthe devices in that environment is intended to be illustrative of thedevice only. It is readily apparent that the devices and methods may beused for tunneling and enlarging working spaces over other longstructures in the body. Various arteries and veins must be exposed andmobilized for other operations, such as popliteal bypass, or a dialysisvein loop. In these operations, a vein must be harvested, and the sitesat which the vein will be attached or anastomosed must also beuncovered. The balloon loaded devices may also be used to gain access toany blood vessel for any type of vascular surgery. For example,communicating veins or perforators in the calf may be exposed bydissecting the muscles deep within the calf to expose these bloodvessels to accomplish a Linton procedure laparoscopically. The devicesand methods may be used to expose those portions of the arteries towhich grafts will be placed.

Other vessels may be dissected from surrounding tissue, such asfallopian tubes, spermatic cords, bile ducts, intestines and others.These vessels may be dissected and mobilized laparoscopically using thedevices and techniques described above. Embodiments of the device mayalso be used to retrofit a scope with a balloon dissector to dissect atunnel under direct vision. Alternatively, the balloon can be used toguide or support a scope within an existing space that needs periodicdilation to permit advancement of the scope. For example, a colonoscopemay be fitted with one of the balloon devices disclosed herein and thedevice used to facilitate insertion of the colonoscope into the colon,especially around the splenic flexure, by inflating the balloon when thetip of the colonoscope approaches the splenic flexure. A urethral scopemay be fitted with the devices disclosed herein to facilitate insertionof the scope into the urethra, which often requires dilation beforeinsertion of a scope. The disclosed devices may be used in combinationwith a scope as an anchor, which while inflated serves to hold the scopein place within the body. While the preferred embodiments of the devicesand methods have been described, they are merely illustrative of theprinciples of the invention. Other embodiments and configurations may bedevised without departing from the spirit of the inventions and thescope of the appended claims.

What is claimed is:
 1. A surgical apparatus comprising:an elongate shafthaving proximal and distal ends, said elongate shaft being plasticallybendable into a curved shape such that said shaft retains the curvedshape while being pushed through body tissue free of naturally occurringopenings; an elongate balloon capable of assuming deflated and inflatedstates on said elongate shaft, said elongate balloon having an axiallength substantially greater than a transverse diameter of said elongateballoon when said elongate balloon is in said inflated state; and afluid passageway in communication with an inflatable space in saidelongate balloon for communicating an inflation fluid to said elongateballoon.
 2. The device of claim 1 further comprising a balloon coversurrounding said elongate balloon.
 3. The device of claim 2 wherein saidballoon cover is formed from a resilient material having sufficientelasticity to collapse said elongate balloon about said shaft when saidelongate balloon is deflated.
 4. The device of claim 3 wherein saidresilient cover comprises a second elongate balloon that may be inflatedindependently of said elongate balloon.
 5. The device of claim 2 whereinsaid balloon cover is a semi-rigid tubular member and is removable fromsaid elongate balloon.
 6. The device of claim 2 wherein said ballooncover is attached to said elongate balloon and separates to release saidelongate balloon upon expansion of said elongate balloon.
 7. The deviceof claim 1 wherein said elongate shaft is a tubular member having alumen therein for receiving a surgical instrument.
 8. The device ofclaim 1 wherein said elongate balloon extends from said proximal end ofsaid shaft to said distal end of said shaft.
 9. A pushable balloondissection apparatus comprising:a tubular member having proximal anddistal ends, said tubular member being plastically bendable into acurved shape such that said tubular member retains the curved shapewhile being pushed through body tissue free of naturally occurringopenings; an elongate balloon capable of assuming deflated and inflatedstates on said tubular member, said elongate balloon having an axiallength substantially greater than a transverse diameter of said elongateballoon when said elongate balloon is in said inflated state; a ballooncover surrounding said elongate balloon; and means for inflating saidelongate balloon.
 10. The device of claim 9 wherein said elongateballoon has an interior space and said tubular member is inside saidinterior space.
 11. The device of claim 9 wherein said balloon cover isformed from a resilient material having sufficient elasticity tocollapse said elongate balloon about said tubular member when saidelongate balloon is deflated.
 12. The device of claim 10 wherein saidresilient cover comprises a second elongate balloon that may be inflatedindependently of said elongate balloon.
 13. The device of claim 9wherein said balloon cover is a semi-rigid tubular member and isremovable from said elongate balloon.
 14. The device of claim 9 whereinsaid balloon cover is attached to said elongate balloon and separates torelease said elongate balloon upon expansion of said elongate balloon.15. The device of claim 9 wherein said tubular member has an internalbore sized to receive a surgical instrument and an open distal end. 16.The device of claim 15 wherein said surgical instrument is a scope. 17.The device of claim 15 wherein said open distal end has a lip partiallyblocking said internal bore.
 18. The device of claim 9 wherein saidelongate balloon is formed from an elastic material and said ballooncover is formed from an inelastic material.
 19. The device of claim 9wherein said elongate balloon extends from said proximal end of saidtubular member to said distal end of said tubular member.